Stone mounting for pulp-wood grinder



Sept. 16, 1958 H. F. METZlG ET AL STONE MOUNTING FOR PULP-WOOD GRINDER 2 Sheets-Sheet 1 Filed March 30, 1956 INVENTORS HARVEY E METZI AND BYRON S. CL

y ARK bdflo nzi s Sept. 16, 1958 H. F. METZIG ET AL 2,851,830

STONE MOUNTING FOR PULP-WOOD GRINDER Filed March 30, 1956 2 Sheets-Sheet 2 INVENTORS HARVEY F. METZIQ Y AND BYRON .S. (JLARK STONE MOUNTING FOR PULP-WOOD GRINDER Harvey F. Metzig, Appleton, and Byron S. Clark, Neenah, Wis.

Application March 30, 1956, Serial No. 575,219

10 Claims. (Cl. 51206.4)

This invention relates to the mounting of a grinding wheel stone men the shaft of a pulp-wood grinder and particularly to the radial support of the stone directly on the shaft and the axial securement of the stone between the two spaced mounting flanges assembled on the shaft.-

According to theinvention as will be described, the stone of the grinding wheel is mounted and assembled on the shaft with one of the flanges regularly fixed thereon and with the other flange temporarily located with respect'to the shaft by means of a shaft collar which is undersized respecting the axial dimension thereof.

The stone is set on the shaft in grout interposed between the stone and the flanges and the shaft is then expanded by means of a heated fluid introduced between the shaft and the stone so that the shaft expands in 1engtl1allowing replacement of the undersized collar with the regular sized collar. When the shaft cools to its normal temperature, the shaft assumes a tensile load which corresponds to the difference between the undersized and the regular sized collar.

The method and apparatus of the, invention. provides for the rapid-heating ofthc steel shaftas by the introduction of steam into the space between the stone and the shaft so that the shaft, by reason of its greater thermal conductivity, expands in length before the corresponding expansion of the stone takes place. The steel shaft and stone referred to *having'approximately the same coefficient of expansion assures thereafter the uniformly tight securement of the stone between the flanges at any higher or lower operating temperatures.

An object of theinvention is to reduce stone failure withan improved securement of the stone on the shaft under a given predetermined compression between the mounting flanges and thefradial support ofthe stone on the shaft.

Another object'of the invention is to eliminate the necessity of screw threads on the shaft for the axial adjustment of the flanges and to provide the radial support of the stone independently of any screw threads 'employed.

Another object is to provide the positive transmission of the torque from the shaft to the flanges independently of the axial securementof'the flanges.

Another object of the invention is to simplify the replacement of the stone which is periodically required.

The drawirigsfurnished. herewith illustrate the best mode of carrying out the invention as presently contemplated and set forth hereinafter.

In the drawings:

Figure 1 is a partially sectioned view of the grinding wheel showing the preliminary installation of the stone and injection of the grout at the ends of the stone;

Fig. 2 is a view similar to Figure 1 and shows the final installation of the stone orithe shaft and between the mou ting flanges a given predeterminedcompression;

United States Patent U 2,851,830 Patented Sept. 16, 1958 Fig. 3 is an enlarged view which is broken away and sectioned to show the temporary jacks and ring or collar for holding the right hand flange and stone in place while the shaft is being heated by steam passed over the shaft by means of the steam lines temporarily attached to the flanges and communicating with the pipes which have been extended through the grout and retaining bulkheads; v

Fig. 4 is an unenlarged elevation of the ring for the jacks for temporarily holding the flange in place as shown in Fig. 3.

The pulp-wood grinding wheel shown in the drawings includes the stone 1 secured between the end journalsZ of the shaft 3. Stone 1 comprises the abrasive blocks 4 which are secured to the reinforced-concrete center cylinder 5 by means of the bolts 6 embedded therein. Cylinder 5 is provided with the central axial bore 7 through which shaft 3 extends and with the alignment bolts 8 radi ally projecting into the opening. After being assembled and located on shaft 3, stone 1 is then centered for balance by adjusting the bolts 8 having their heads in direct contact with the shaft.

The bulkheads 9 and sealing material 10 are inserted in the ends of bore 7 between shaft 3 and cylinder 5 to close the bore. Bulkheads 9 are located against the bolts 3 to define the annular chamber 11 which extends around shaft 3 and sealing material 10 is employed to make the chamber pressure-tight as required.

The flanges 12 and 13 at each end of stone 1 are similar or identical and are rotatively fixed relative to shaft 3 by keys 14.. The flanges are spaced from material ltl and, referring to Figure 1, are axially held to a given maximum distance apart on the shaft by the collars 15 and 16, respectively, fitting in the annular grooves 17 and 18 0f the shaft. Each of collars 15 and 16 comprise two separate complementary parts for assembly on the shaft. Collar 16 is of a width or axial dimension which is significantly less than the Width of collar 15 and of grooves 17 and 18 as will appear hereinafter.

The grout 19 is injected by the pipes 20 temporarily fitted in the threaded holes 21 of flanges 12 and 13. During such injection, the stone is secured between the flanges by the threaded plugs 22 in flange 12 and the hydraulic cylinders 23 temporarily carried by flange 13. Hydraulic pressure applied to cylinders 23 forces the pistons 24 against stone 1 and the stone is accordingly forced against plugs 22 so that flanges 12 and 13 are squarely and firmly located against collars 15 and 16. The dowels 25 are inserted in the holes 26 and 27 of flanges 12 and 13 with the inner ends thereof extending to the sealing material 10 to form cores in the grout. The retaining bands 28 having vent pipes 29 shown in Figure I serve to retain the grout during injection and are removed after the grout has set.

When grout 19 has set, the grout between material 10 and flanges 12 and 13 provides the radial support of stone 1 on shaft 3. The grout 19 between flanges 12 and 13 and ends of stone 1 provides the axial support of the stone under compression between the flanges. Such compression is provided by the replacement of collar 16 with the collar 30 shown in Fig. 2 and having a width greater than collar 16, and which results in a tensile load on shaft 3.

According to the invention, such replacement is effected by securing flanges 12 and 13 against relative parting movement and expanding shaft 3 without also expanding stone 1 by rapidly heating the shaft and making the replacement referred to before stone 1 has become appreciably heated.

Collar 16 shown in Figure 1 is provided with the threaded holes 31 for receiving cylinders 23 which are mounted as shown in Fig. 3 with the pistons 24 engaging flange 13 and may comprise separate complementary parts 32 as shown in Fig. 4. With the cylinders carried by collar 16, hydraulic pressure maintained within cylinders 23 biases flanges 12 and 13 toward each other so that the movement of shaft 3 relative to flange 13 during expansion of the shaft does not pull the flanges loose from the grout. By drilling out dowels 25 and through material 10 and bulkheads 9 into chamber 11.

.the holes 26 and 27 of flanges 12 and 13 are extended through grout 19 and into the chamber for the insertion of steam pipes 33 and 34 as shown in Figs. 2 and 3. The steam is introduced into chamber 11 as by the steam line 35 connected to flange 13 to communicate with pipe 34 and return pipe 33 which should be near the bottom of chamber 11 is to be similarly connected to a condensate return line, not shown.

When the installation of the stone has been completed the plugs 36 are installed in the threaded ends of holes 26 and 27 to exclude foreign matter from pipes 33 and 34 and plugs 37 are similarly employed to replace cylinders 23 when removed from flange 13.

It has been found that a shaft for a stone four feet in length can be adequately heated in 60 to 100 minutes with steam at 70 lbs. gage pressure and that such heating allows a period of up to 20 minutes thereafter for replacing collar 16 with collar 30. At 70 lbs. pressure, the steam will rapidly heat shaft 3 to about 300 F. while the inner portions of cylinder of stone 1 will ordinarily be heated to or slightly above 212 P. so that upon removal of such steam pressure the condensate remaining at the bottom of chamber 11 boils out. Thereafter and upon relieving the pressure in cylinders 23, the replacement of collar 16 with collar 30 may be readily effected.

Only the innermost portion of cylinder 5 of stone 1 becomes appreciably heated in the period of time referred to and the expansion of shaft 3 occurs before the corresponding expansion of stone 1 by reason of the greater thermal conductivity of the steel of shaft 3 and the greater cross-section and specific heat of the stone.

The invention overcomes the need of screw threads where they cannot in practice provide the firm radial or axial support of the flanges as is required. in the present invention, the radial support of the stone on the shaft is directly provided by the grout located between material and the flanges and such support is provided irrespective of the fit of'the flanges on shaft 3. Flanges 12 and 13 are squarely held against collars and 30 in grooves 17 and 18 and with shaft 3 under a tensile load which may be readily predetermined by the different dimensions of collars 16 and 30. Such dimensions may be provided also by one or more shims, not shown, to be inserted between the flange and the collar. The tensile load referred to provides the permanent securement of the stone under compression which can be depended upon to remain Within acceptable limits throughout the regular service of the stone.

Replacement of stone 1 is readly effected by reheating the shaft as described which allows the ready removal of collar 30. The uniformity of the pressure applied to the ends of the stone and the improved radial and axial support of the stone on the shaft reduces stone failure and mechanical complications which contribute thereto.

Various modes of carrying out the invention are contemplated within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

1. The method of securing a grind-stone on a metal shaft between the two mounting flanges of the shaft as in a pulp-wood grinder which method comprises effecting the expansion of the shaft by rapidly applying heat to that part of the shaft between the flanges to expand the shaft, fixing the flanges on the shaft upon a given expansion of the shaft prior to the expansion of the stone and thereafter allowing the shaft to cool to the temperature of the stone, the contraction of the shaft upon such cooling providing the uniform tension of the shaft in the desired securement of the stone by compression between the flanges throughout the regular service of the grind-stone.

2. The method of securing a grind-stone on a metal shaft between the two mounting flanges of the shaft as in a pulp-wood grinder which method comprises fixing the distance between said flanges on the shaft while aiiowing movement of the shaft relative to at least one of said flanges, setting the stone between said flanges in cementitious material, rapidly applying heat to that part of the shaft between the flanges to expand the shaft, fixing the flanges on the shaft upon a given expansion of the shaft prior to the expansion of the stone and thereafter allowing the shaft to cool to the temperature of the stone, the contraction of the shaft upon such cooling providing the uniform tension of the shaft in the desired securement of the stone by compression between the flanges.

3. The method of securing a grind-stone on a metal shaft between the two mounting flanges of the shaft as in a pulp-wood grinder which method comprises locating at least one of said flanges on the shaft with an undersized temporary collar whereby the dimension between the flanges is oversized, setting the stone between said flanges in cementitious material, rapidly applying heat to that part of the shaft between the flanges to expand the shaft, at the same time restraining the relative movement of the flanges, replacing said undersized collar with a regular sized collar before the expansion of the stone takes place, and thereafter allowing the shaft to cool, said collars being provided with axial dimensions having a difference which corresponds to the calculated tension of the shaft in the desired securement of the stone by compression between the flanges upon subsequent cooling of the shaft.

4. The method of securing a grind-stone on a metal shaft between the two mounting flanges of the shaft as in a pulp-wood grinder which method comprises fixing the distance between said flanges on the shaft while allowing movement of the shaft relative to at least one of said flanges, providing a fluid-tight chamber within the stone and around said shaft and between said flanges, circulating a heated fluid through said chamber for a limited period of time so that the shaft by reason of its greater thermal -conductivity expands in length before the expansion of the stone takes place, fixing the flanges on the shaft prior to said corresponding expansion of the stone, and thereafter allowing the shaft to cool to the temperature of the stone, said shaft and stone having approximately the same coeflicient of expansion whereby the nearly uniformly tight securement of the stone between the flanges is provided at any higher or lower operating temperatures.

5. In a grinding wheel as for pulp-wood grinders, a shaft having spaced flanges removably fixed thereto, a stone having a central axial bore, said stone being assembled on said shaft with the shaft extending through said bore and being secured by compression between said flanges, means including said flanges closing the ends of said bore and defining a fluid-tight chamber extending around the shaft and between said closure means, and fluid conduit means extending from said chamber and having external fittings for the circulation of a heated fluid through said chamber as from supply means connected to said fittings for quickly expanding said shaft and provide for the removal and insertion of one of said flanges prior to the corresponding expansion of the stone and thereby provide for the assembly and disassembly of said stone and shaft.

6. In a grinding wheel as for pulp-wood grinders, a shaft having spaced flanges removably fixed thereto, a

stone having a central axial bore, said stone being assembled on said shaft between said flanges and with the shaft extending through said bore, cementitious material extending into each end of said bore of the stone and radially supporting the stone on said shaft, said material being disposed also between each end of the stone and the corresponding flange and said stone being secured by compression between said flanges, said material and said flanges closing the ends of said bore to define a fluidtight chamber extending around the shaft and between said closure means, and fluid conduits from said chamber having external supply fittings for the circulation of a heated fluid through said chamber as from supply means connected to said fittings for quickly expanding said shaft and the removal of at least one of said flanges prior to the corresponding expansion of the stone.

7. The method of securing a grind-stone on a shaft which method comprises providing spaced annular abutment means on said shaft and flanges to fit on the shaft and between and against the respective abutment means, securing said flanges squarely against said abutment means with the stone disposed on the shaft and between said flanges, sealing the ends of said bore at spaced points near the ends of the stone to define a fluid-tight chamber, providing fluid supply means to and from said chamber, securing the flanges at the corresponding ends of the stone against the respective abutment means, injecting grout in the space between the flanges and ends of the stone and into the bore between the stone and shaft up to said sealing means, securing said flanges against the ends of the stone while circulating a heated fluid through said fluid supply means and chamber to rapidly expand the shaft before the corresponding expansion of the stone, and before such expansion of the stone applying other abutment means on said shaft and having a dimension which imposes a tensile load on the shaft upon cooling and provides a corresponding securem-ent of the stone under compression between said flanges.

8. The method of securing a grind-stone on a shaft extending through the bore of the stone which method comprises providing spaced annular abutment means on the shaft and flanges to fit on the shaft at each end of the stone and against said annular abutment means, sealing the ends of said bore at spaced points near the ends of the stone to define a fluid-tight chamber therebetween, securing said flanges squarely against said abutment means a given distance apart as determined thereby, providing fluid supply means to and from said chamber, injecting and setting grout in the space between the flanges and ends of the stone and in the bore between the stone and shaft up to said sealing means, securing said flanges against the ends of the stone and circulating a heated fluid through said fluid supply means and chamber to rapidly expand the shaft before the expansion of the stone, before such expansion of the stone applying other abutment means on said shaft having a dimension which would normally determine a distance between flanges less than that referred to, and allowing said shaft to cool and contract to its normal dimension, such contraction imposing a tensile load on the shaft upon cooling which provides a corresponding securement of the stone under compression between said flanges.

9. A pulp-wood grinder and the like, comprising a grinding stone having an axial bore therethrough, a metal shaft extending through said bore, and flanges fixed on said shaft and engaging said stone at the opposite ends of said bore to rigidly support the stone upon the shaft, said flanges being held in longitudinal compressing engagement with said stone by a substantial residual longitudinal tension stress formed in said metal shaft when the latter is cooled from a heated condition.

10. The method of assembling a pulp-wood grinder and the like wherein the grinding stone has an axial bore receiving a supporting metal shaft therefor, comprising fixing a flange upon the shaft for engagement with one end of the stone, temporarily fixing an opposing flange upon the shaft for engagement with the opposite end of the stone and leaving the shaft free to move as by longitudinal expansion through said latter flange, applying sealing compound between the flanges and the stone and leaving a radial space between the stone and the central portion of the shaft between the flanges, circulating a heating medium in said radial space to quickly heat the shaft and thereby expand the same longitudinally before substantial heat expansion of the stone, and securing said temporarily secured flange upon the shaft while the latter is expanded whereby upon cooling of the shaft the flanges effectively compress the stone and effect a residual tension stress in the shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,386,743 Trudel Aug. 9, 1921 1,920,204 Larsson Aug. 1, 1933 2,693,670 Perry Nov. 9, 1954 FOREIGN PATENTS 848,150 Germany Sept. 1, 1952 

